Development of variable operation, pressure-type quench relief valve for superconducting magnet systems

A variable operation, pressure-type quench relief valve (VQRV) has been developed by the High Energy Accelerator Research Organization (KEK) for superconducting magnet systems. It is based on the Kautzky valve, featuring a long extension structure, a high radiation-proof gas seal with Poly-Ether-Ether-Ketone (PEEK) and an actuator driven by differential pressure between a process value and a set value. The VQRV was tested under a high radiation environment up to 2.5 MGy. The gas leak rate and heat load were measured at 4.2 K. A measured heat loss of less than 1.5 W and a seat leakage rate of 4.5 x 10-7 kg/sec are low enough for cryogenic system operation in the J-PARC neutrino beam line. The design and test results of the VQRV are described in this technical report. (author)